The effective use of renewable energy has recently taken place. Wind turbine generator systems have been developed around the world as an especially profitable project. At present, wind power generating facilities which have been constructed are mainly established at coasts on-shore.
But, wind as driving force of the wind power generator is generally stronger on the sea comparing to on land which has more disturbances, and the wind direction off-shore is more stabilized. So, because not only more output can be obtained off-shore but also it doesn't cause noise pollution, establishing the wind turbine generator systems not on-shore but off-shore is preferable.
Usually, the wind turbine generator system has a nacelle supporting the rotor which is rotated by blades. In the nacelle, a generator and other things are contained. The generator is rotated by a rotation of a main shaft connected with the blades. The nacelle is configured to be supported by the tower. The generator contained in the nacelle generates a large amount of thermal energy, and additionally in case the wind turbine generator systems are established off-shore, some consideration is necessary for not being affected by salt damage from sea water.
Considering these problems, namely, both cooling the generator contained inside the nacelle and removing influence of the salt damage from sea water, the patent literature 1 has been proposed.
In patent literature 1, wind turbine generator systems established off-shore are described, they have a circulation line which circulates sea water in the tower and in the nacelle, and a compressor which provides the sea water in the nacelle. In one of the wind turbine generator systems, after the sea water is circulated in the nacelle, the sea water is discharged either from the bottom of the tower or from the nacelle. In the other of the wind turbine generator systems, the circulation line is a closed system, and after cooling water is circulated in the nacelle, the cooling water is cooled by exchanging the heat with sea water at the bottom of the tower. Because of said features, the heat generated by the generator is cooled by exchanging the heat inside the wind turbine generator system while sealing inside and outside the wind turbine generator system so that the influence of the salt content in the sea water could be removed.